Well drilling platform



June 15, 1965 D. DE VRIES WELL DRILLING PLATFORM Filed Sept. 15, 1962 7Sheets-Sheet l INVENTOR:

D. DE VRIES HIS AGENT June 15, 1965 D. DE VRIES 3,189,093

WELL DRILLING PLATFORM Filed Sept. 13, 1962 '7 Sheets-Sheet 2 |NVENTOR=D. DE VRIES 9. MM 4 I HIS AGENT June 15, 1 D. DE VRIES 3,189,093

WELL DRILLING PLATFORM Filed Sept. 13, 1962 7 Sheets-Sheet 3 INVENTOR:

D. DE VRIES I a H m IS AGENT June 15, 1965 D. DE VRIES 3,189,093

WELL DRILLING PLATFORM Filed Sept. 13, 1962 7 Sheets-Sheet 4 FIG. 6

FIG. 7

INVENTOR D. DE VRIES S AGENT June 15, 1965 D. DE VRIES 3,189,093

WELL DRILLING PLATFORM Filed Sept. 13, 1962 7 Sheets-Sheet 5 FIG. 9

INVENTOR:

D. DE VRIES BY: H7114 (l-29 HIS AGENT June 15, 1965 D. DE VRlES WELLDRILLING PLATFORM '7 Sheets-Sheet 6 Filed Sept. 15, 1962 INVENTOR:

D. DE VRES BY:

HIS AGENT D. DE VRIES WELL DRILLING PLATFORM June 15, 1965 7Sheets-Sheet 7 Filed Sept. 13, 1962 INVENTOR:

0. DE VRIES BYI H7 1% HIS AGENT United States Patent 3,189,093 WELLDRILLKNG PLATFQRM Douwe de Vries, Metairie, La., assignor to Shell 013i(Zompany, New York, N.Y., a corporation of Delaware Filed Sept. 13,1962, Ser. No. 223,385

8 Claims. (Cl. 1'e646) v This invention relates to apparatus for use indrilling,

completing and working over operations in oil and gas wells at offshorelocations, and pertains more particularly to a method and apparatus forhandling heavy well equipment on a drilling platform and subsequentlylowering the equipment from the platform down through the water to aWellhead assembly.

In an attempt to locate new oil fields, an increasing amount of welldrilling has been conducted at offshore locations, such for example, asoff the coast of Louisiana, Texas and California. As a general rule, thestrings of casing in a well, together with the tubing string or strings,extend to a point above the surface of the water where they are closedin a conventional manner that is used on land wells, with a conventionalwellhead assembly being attached to the top of the casing. Recently,methods and apparatus have been developed for drilling and completingwells wherein both the well casinghead and subsequently the wellheadassembly and easing closure devices, are located underwater at a depthsuflicient to allow ships to pass over'them. Preferably, the casingheadand wellhead assemblies are located close to the ocean floor. In orderto install well drilling equipment underwater at depths greater than theshallow depths at which a diver can easily operate, it has beennecessary to design entirely new equipment for this purpose.

Time is of the essence in offshore well drilling operations which maycost in the order of $10,000 per day. Thus, it is desirable to have asmuch of thewell equipment preassembled as possible so that thepreassembled sections can be installed in the shortest time possible.The term well equipment as used hereinbelow refers to any piece orassemblageof equipment used in drilling or working-over a well, such forexample, as a drilling wellhead assembly or a blowout preventer stack,which may comprise one or more-blowout preventers connected together endto end. above a wellhead connector or other device adapted to secure theblowout preventers to a casinghead. The term well equipment alsoincludes production equipment, such for example, as a productionwellhead assembly, commonly known as a Christmas tree, which controlsthe flow of oil or gas from a well and contains various components suchas valves, valve operators, pressure-sensing devices, etc. Forunderwater wells, the essential components of a producing wellheadassembly are normally encased in a container to reduce corrosion or theaccumulation of marine growth.

Well equipment in the form of a production wellhead assembly orproduction package, or in the form of a stack of blowout preventers foruse in drilling a high pressure well, form a sizeable load or package ofequipment which, depending upon the drilling conditions, may be feettall, 8 feet wide and may weigh as'much as 80,000 pounds. It is mostdiflicult to handle and maneuver an equipment 7 package of this size andweight on a drilling platform,

especially one that is in a floating position over the drill site. Inorder to lower equipment of this type into position at the wellhead, thehoist of the derrick on the drilling platform is generally used.However, due to the size of many of these equipment packages, it is notpossible to lower the equipment package through the derrick floor asthere is not enough room usually even between the structural members ofthe derrick floor to pass a package of this size. At the same time,costly delays would be ice encountered in taking out a rig or derrickfloor in order to lower an equipment package therethrough, andsubsequently putting the floor back in place.

It is therefore a primary object of the present invention to provide adrilling vessel, platform or barge provided with suitable apparatus forhandling large loads of equipment used during the drilling or workingover of a well.

A further object of the present invention is to provide a drillingplatform of suitable design whereby heavy loads of equipment may bepreassembled on deck, or at another point, and subsequently transferredto a position below the derrick of the drilling platform whereby thenecessary connections to the equipment may be made before lowering theequipment to a wellhead.

Another object of the present invention is to provide a method andapparatus for lowering a well equipment package through the main deck ofa drilling platform to one side of a derrick thereon, moving the load toa position under the center line of the derrick, making the necessaryequipment connections to the load, and subsequently lowering theequipment load into place at an underwater well assembly.

Still another object of the present invention is to provide guide linesbetween a floating drilling platform and an underwater wellhead assemblywhereby equipment may be lowered on the guide lines from the vessel tothe wellhead, the vessel also being provided with means for moving theguide lines to one side of the center line of the well and the derrickand maintaining constant tension on the guide lines in their offsetposition while moving equipment into place below the derrick of thebarge prior to lowering the equipment to the wellhead.

These and other objects of this invention will be understood from thefollowing description taken with reference to the drawing, wherein:

FIGURE 1 is a diagrammatic view taken in longitudinal projectionillustrating a floating drilling platform positioned on the surface ofthe ocean;

FIGURE 2 is a plan view of the drilling platform of FIGURE 1;

FIGURE 3 is an enlarged diagrammatic view taken in longitudinalprojection of a portion of the drilling platform of FIGURE 1illustrating the lower portion of a derrick positioned on the drillingplatform and an auxiliary deck positioned below the derrick;

FIGURE 4 is an enlarged diagramamtic view of the auxiliary deck ofFIGURE 3 showing the load supporting means;

FIGURE 5 is a view taken along the line 5-5 showing in enlarged detailthe retractable load supporting means on the auxiliary deck of FIGURE 4;

FIGURE 6 is a plan view taken in enlarged detail of the sheave dolly forthe equipment guide lines shown in FIGURE 3;

FIGURE 7 is a view taken along the line 7-7 of FIG- URE 6 showing inenlarged detail the arrangement of sheaves on the sheave dolly;

FIGURE 8 is a plan view showing the arrangement of another form of asheave dolly mounted on tracks together with a pair of load carryingdollies;

FIGURES 9, 10, 11 and 12 are longitudinal views of a portion of thedrilling platform illustrating successive steps in the transfer of anequipment load from a crane to load-supporting dollies, to retractableload-supporting means on the auxiliary deck and thence to the hoistsystem of the derrick;

FIGURE 13 is a side view taken in enlarged detail illustrating one formof a drive mechanism for the load carrying dollies on the presentdrilling platform; and,

FIGURE 14 is a view of the load-carrying dolly assembly and tracks ofFIGURE 13 taken along line 14-14.

Referring to FIGURE 1 of the drawing, a drilling platform, vessel orbarge, of any suitable fioatable type, is generally represented bynumeral 11 and is illustrated as floating on the surface of a body ofwater 12, and substantially fixedly positioned over a preselecteddrilling location by suitable barge or vessel positioning means, or bybeing anchored to the ocean floor by suitable anchors (not shown)connected to the anchor line 14 and 15. Equipment of this type may beused when carrying on well drilling operations in water depths varyingfrom about 100 to 1500 feet or more. A typical drilling platform maycomprise a hull made up of vertical buoyant members 16, 17, 18, 19, 26and 21 secured to their lower end to horizontal buoyant members 22, 23,24, 25, 26 and 27. The vertical buoyant members 16-21, together withadditional vertical support members 28, form a support for the main deck30 of the drilling platform 11. The main deck 30 may be provided with aconventional drilling slot (not shown) or may be provided with anoutwardly extending section 31 which overhangs the hull member 22 on oneside of the drilling platform. Suitable braces 32 and 33 may be utilizedto support the overhang or extension section 31 of the main deck 30.

Hanging from the overhang or extension portion 31 of the main deck 30are vertical support members 34 and 35 which support an auxiliary deck36 below the main deck overhang 31. The drilling platform 11 is providedwith a suitable derrick 37 having conventional fall lines 38, travelingblock 39 and hook 40 or elevator 40a (FIGURE 3). A crane 41 ispositioned on the main deck 30 of the drilling platform 11 for hoistingequipment from barges or smaller boats drawn along side the drillingplatform. In the arrangement of the present invention, FIGURE 1illustrates drilling operations being carried on with the use of a pairof guide lines 42 and 43 for guiding equipment from the drillingplatform down to an underwater wellhead or other underwaterinstallation. It is to be understood, however, that the drillingplatform of the present invention could also be employed to drillunderwater wells without the use of guide lines 42 and 43.

Instead of using a two line guide system as shown in FIGURE 1, the guideline system shown in FIGURES 3 and 6 comprises three main guide lines44, 45 and 46 passing over sheaves 47, 48 and 49 (FIGURE 6) which arearranged in a triangle during lowering and/ or drilling operations aboutthe axis of the well represented by numeral 50. The main guide lines 44,45 and 46 are employed to guide the major portion of apparatus fromdrilling platform 11 down to the underwater wellhead. Thus, all of thecomponent parts of a drilling wellhead assembly or a production wellheadassembly which are mounted in an end to end relationship on the sameaxis are sent down the main guide lines. In addition, if desired, a pairof auxiliary guide lines 51 and 52 passing over sheaves 53 and 54 may beemployed and are positioned generally to one side of the main guidelines 44, 45, and 46 whereby equipment mounted to one side of a wellheadassembly may be lowered into place. All of the guide lines 44, 45, 46,51 and 52 are run over suitable sheave arrangements, such for example assheaves 55, 56, 57 and 58 to constant-tension hoist means 69,diagrammatically shown in FIGURE 3 as being positioned on the base 61 ofthe derrick 37 for ease of illustrating purposes. It is to beunderstood, however, that the constant-tension hoist means could bemounted in any other suitable location, preferably on the main deck ofthe drilling platform 11 to facilitate repairs on the guide line system.

As shown in FIGURE 6, the sheaves 48, 49, 53, and 54 are fixedly securedto a sheave dolly or carriage 62 provided with two sets of wheels 63 and64 which are mounted for movement along horizontal tracks 65 and 66. Thesupport pulley 47 for guide line 4-4 is positioned at the end of atelescoping or retracting arm 67 which is retractable in a housing 63which in turn is fixedly secured below track 65. Thus with the arm 67retracted in the housing 63 and the sheave dolly moved to the right inFIGURE 6 a substantial distance, a greater amount of space is provideddirectly over the center line 50 of the well whereby large packages ofequipment can be lowered through the vertical opening in the auxiliarydeck 36 (FIGURE 1). In FIGURE 6, the vertical support members for theauxiliary deck 36 are shown as elements 34, 35, 34a and a. Suitablecat-walks 69 and 76 may be provided. In FIGURE 7 the end of the housing71 around the wheels 64 and 64a is shown as extending to the rightbeyond any of the sheaves 49, 48, 54 and 53 to serve as a bumper againstthe stop member 72. The sheave dolly 62 may be provided with suitablebooks 73 by which the sheave dolly 62 (FIGURE 7) may be hooked to a pairof load carrying dollies 74 and 75 (FIGURE 8). The hooks 73 would beattachable to rings 76 and 77 on the adjacent edge of the nearestloadcarrying dolly 75 so that the two dollies could be moved together.

In FIGURE 8 the sheave dolly 62a differs from that illustrated in FIGURE6 in that only two main guide lines 46a and a are employed which passover sheaves 48a and 49a respectively. When equipment was being loweredto or raised from a wellhead with the sheave system of FIGURE 8, thesheave dolly 62a would be positioned on the tracks 65 and 66 so that theguide lines 45a and 46a would pass over their respective sheaves 48a and4% at points diametrically opposite the center line of the well.

As shown in FIGURE 8 the load carrying dolly 74 is provided with wheels78 and 7811 which ride on tracks 65, and wheels 79 and 7% which ride ontracks 66. In addition, the dolly 74 may be provided with a pair ofbumpers 80 and 80a adapted to engage corresponding and oppositely-facedbumpers 83 and 83a carried by the other load carrying dolly 75. Thelatter dolly 75 is provided with wheels 81 and 81a which ride on trackand wheels 82 and 82a which ride on track 66. In FIGURE 9 it may be seenthat the tracks 65 and 66 are preferably mounted close to the deck ofthe drilling vessel or its overhang extension deckportion 31. Secured tothe bottom of the dollies 74 and (FIGURE 9) are suitable load-connectingmeans such for example as a pair of slings 84 and 85. Although twoslings are illustrated, it is preferred that at least three be employedso as to reduce the tendency of an equipment package or load 86 to swingwhen it is secured to the lower end of the slings. If three slings areused, two would be secured to one of the dollies and one to the other.The slings are preferably secured to the dollies midway between thewheels in order to get better weight distribution. If desired, a spacerbar (FIGURE 9) may be connected between the bumpers a and 83a to securethe load-carrying dollies 74 and 75 together when a load is slungtherefrom. The length of the spacer bar would be determined by the sizeof the package or load 86 which is being handled.

Any suitable form of prime mover means may be employed to move theload-carrying dollies or carriages 74 and 75 along their tracks 65 and66. Thus, for example hydraulic jacks, screw drives, orelectrically-driven gear drives may be employed. One suitable form ofdrive mechanism for the dollies 74 and 75 is illustrated in FIG- URES 13and 14. In this arrangement the drive mechanism comprises two sets ofdrive chains 90 and 90a, and 91 and 91a. Preferably, an air-driven motor92 is employed to reduce the fire hazard in well drilling operations.This motor drives two pairs of sprockets 94 and 94a which drive pairs ofchains 90 and 91 and 90a and 91a, respectively. As shown in FIGURE 13the drive chain 99 extends the length of the track 66 and passes over anidler sprocket 96 positioned at the other end of the tracks 66. It is tobe understood that each of the chain drives 90, 90a, 91 and 91a is acontinuous chain having an idler sprocket at the outer end thereof.Preferably, the air driven motor 92 is provided with proper reductionvgearing and air-actuated clutches whereby either one of the dolliescould be driven independently of the other. Dolly 74 is provided with apair of out wardly and downwardly-extending arms 57 and 97a which areoperatively connected to the drive chains 90a and 91a so that the chainswill propel the dolly 74 along the tracks 65 and 66. In a like manner,the other dolly 75 is provided With a pair of outwardly-extending arms98 and 98a which are operatively connected to the other pair of drivechains 90 and 91, respectively. With this and other similar arrangementsthe load-carryingdollies 74 and 75 can be either driven simultaneouslyor one at a time, or one dolly can be driven to push or pull the otherdolly and/ or pull the sheave dolly 62. Normally, the sheave dolly 62 isprovided with suitable means for anchoring it to the track or tracksupport means in a fixed position such, for example, as by one or morelocking pins 99 which would extend downwardly through the dolly carriageand the I-beam 100 supporting the tracks 66. Each dolly 74 may beprovided with sling rings or other connections 101 and 101a by whichslings can be secured to the under portion of the dolly.

In order to provide a large opening, say 20 feet square through theauxiliary deck 36 and directly underneath the hoist system of thederrick of the drilling platform, that portion of the auxiliary deck 36(FIGURE 4) directly below the hoist system is made removable or open-'able, preferably in the form of a pair of trap doors 102 and 103 whichdrop downwardly but normally are locked in a horizontal position. Tofacilitate the handling of large and heavy loads beneath the derrick ofthe drilling platform, the auxiliary deck 36 is preferably provided withload-supporting platform means which is movable and/ or retractable froma position in which it extends across the center of the opening 104through the auxiliary deck 36, to a position where it is retractedentirely from the opening leaving the full opening through whichequipment may be lowered. As shown in FIGURES 4 and 5 the retractableplatform comprises a pair of parallel spaced beams 105 and 106 hung froma suitable support assembly 107 which is positioned outside the verticalsupport member 35. The space between the vertical support members 35 and35a is equal to the opening through the auxiliary or spider deck 36. Thesupport assembly 107 comprises, for example, a support beam 108 to whichis fixedly secured a series of roller bearing mountings 109 above thebeam 106 and 110 below the beam. Suitable prime mover means are providedfor extending or retracting the beam 106 across the opening in thespider deck 36. For example a motor 111 is provided to drive as througha worm gear, a drive gear 112'which engages a gear rack 113 on thebottom of the beams 106 and 105. In FIGURE 5, the beam 106 is shown inits nearly extended position, being adapted to seat in recess 114 priorto placing a load thereon.

The method of the present invention is illustrated with reference toFIGURES 2, 3, 10, 11 and 12 of the drawing. As shown in FIGURE 2, thecrane 41 can be turned so as to project out over the side of thedrilling platform deck 30 so as to hoist an equipment load or packagefrom an auxiliary barge or vessel on the surface of the water anddeposit the load or package on the deck 30. Adjacent the derrick 37, aportion of the deck 30 and extension 31 is removable to form a verticalopening 116 through the main deck. This opening 116 may be of any size,preferably in the order of 20 feet square, depending upon the equipmentloads to be lowered therethrough. The tracks 65 and 66 (FIGURE 8) arepositioned on either side of the vertical opening 116 (FIGURE 2) andbelow the main deck 30 and extension 31 thereof. In FIGURE 3, the crane41 is shown as it lowers the equipment package or load 86 to the decklevel above the 6 vertical opening 116 (FIGURE 2) therein. At this timethe dollies 74 and 75 (FIGURE 3) would be spaced apart sufiiciently toallow the load 86 to be lowered between them by the crane to theposition shown in FIGURE 9 of the drawing. At this time the equipmentpackage 86 would be supported by the sling 118 depending from the crane41. At the time of lowering if the spread bar 87 separates theload-carrying dollies 74 and 75 suificiently the load 86 may .be loweredthrough the dollies. If necessary, the spacer bars 87 may bedisconnected at the time the load 36 is being lowered between thedollies 74 and 75.

With the load in the position shown in FIGURE 9, the slings 84 and 85are connected between the load 86 and the load-carrying dollies 74 and75. After installing the spacer bars 87 the hoist line 118 of the crane41 is slacked off slowly until the load 86 is suspended from the slings84 and 85. The sling 117 is then disconnected from the load 86 andpulled out of the way with the crane 41. The motor 92 (FIGURE 4) anddrive chains are actuated to move the load-carrying dollies 74 and 75and the load 86 from a position beneath the vertical opening 116 (FIGURE2) in the deck 30 to a position beneath the rotarytable 119 (FIGURE 3)positioned on the derrick floor 120. In the event that the rotary table112 has been removed to provide .an opening through the entire platformduring this equipment handling operation, the load 86 is hung from thedollies 74 and beneath the center line of the derrick, or the centerline of its hoist system, as shown in FIGURE 10.

At this time a sling 121 is connected to the equipment load 86 and runsover the hook 40 of the derrick hoist system; The weight of theequipment load 86 is picked up by the hook 40 slightly so that theweight is slacked oif of the slings 84 and which are then disconnectedfrom the equipment package 86.

The equipment package 86 used for illustration purposes comprises aproduction wellhead assembly having connector means 122 depending fromthe bottom thereof for connecting it to a well casinghead. In order toprotect this downwardly-depending wellhead connector 122, a base stand123 is temporarily connected to the load 86. Prior to setting the load,on the load supporting beams and 106 (FIGURE 11) the base stand123(FIGURE 10) has been removed. The hook 40 is then lowered until the load86 is positioned on the load-supporting retractable beams 105 and 106 asshown in FIGURE 11. Subsequently, if desired, a pipe string or tubingstring 124 may be run up from the undesirde of the auxiliary or spiderdeck 36 and the upper end of the tubing string 124 connected to thewellhead connector 122.

The hook 40 is then l olwered slightly to slack oh tension on the sling121 which is then removed from the equipment load 86. A pipe string 125(FIGURE 12), commonly known as a running string, is secured in anysuitable manner to the top of the equipment package 86 and is used forlowering the equipment package down through the vertical opening in theauxiliary deck posi-' tioned below the rotary table 119. The elevator40a carried by the traveling block 39 (FIGURE 3) of the hoist system ofthe deck engages the running string 125 (FIG- UR-E 1 2) as it is lowereddownwardly from the drilling platform together with the equipmentpackage 86. Additional length of pipe are added to the top of therunning string 125 as the running string 125 and the package 86 aremoved in stages downwardly into position at the under'water well. Priorto lowering it through the auxiliary deck 36 the elevator picks up theload slightly so that the load supporting beams 105 and 106 may beretracted in a manner described hereinabove with regard to FIGURES 4 and5. Subsequently, with the vertical opening in the auxiliary deck nowclear, the equipment package 86 is free to move down into the water.While the above method has been described with regard to hanging theequipment package 86 from the load-carrying dollies 74'and 75 moving ontracks 65 and 66, it is quite apparent that the tracks 65 and 66 couldbe located on or close to the auxiliary deck 36 at the level of or abovethe loadsupporting beams 105 and 106 so that the equipment package 86could rest on the dollies 74 and 75 rather than being suspended from thedollies. However, it is preferred to hang the equipment load from thedollies 74 and 75 as better control of the package is provided on adrilling platform which may be heaving and rolling with the motion ofthe sea. It would be more difficult to tie the vertical package down toone or more dollies or platforms positioned beneath it. Additionally, itis pointed out that while the above apparatus and method is describedwith regard to employing a pair of load-suporting beams 105 and 106, itis to be understood that for certain operations, after moving thedollies 74 and 75 and its load 86 to the position shown in FIGURE 10,the pipe string 125 (FIGURE 12) could at that time be connected to thetop of the equipment package 86 rather than first lowering the package86 down on the load supporting beams 105 and 106. However, in the eventthat any substantial operations are to be carried out or adjustments tobe made with regard to the equipment package 86 it is preferred that thepackage 86 be lowered down to rest on the retractable load-supportingplatform or beams 105 and 106. At the time the equipment package isbeing positioned over the vertical opening extending through thedrilling barge, that is, through the rotary table through the deckportion below the table and through the auxiliary deck 36, the sheavedolly 62 (FIGURES 3 and 6) and the retractable sheave arm 67 are movedaway from the center line of the well 50 so that the guide lines 44, 45,46, 51 and 52 are moved out of the way so as to facilitate placing thepackage 86 on the retractable support means 105 and 106. To aid inlowering the equipment package 86 (FIGURE 3) to an underwater well, thepackage 86 may be provided with two or more guide arms 127 and 128adapted to engage and slide along the guide lines 44, 45 and/or 46. Whenthe package 86 is ready to be lowered the sheave dolly 62 and theretracting arm 67 are returned to their normal position shown in FIGURE6, and the guide arms are engaged to the guide lines.

I claim as my invention:

1. In well drilling, completion and work-over operations carried on atoffshore location from a drilling platform having a derrick and a hoistsystem therein, a method of handling equipment prior to running saidequipment to an underwater wellhead, said method comprising (a)positioning an equipment load to one side of a derrick on a drillingplatform,

( b) lowering said equipment load from the level of the derrick base toa level on said drilling platform entirely below said derrick base andto one side thereof,

() positioning said equipment load at said lower level for lateralmovement thereat,

(d) moving said equipment load laterally at said lower level to aposition underneath the hoist system of said derrick,

(e) transferring said equipment load from said load moving position toload-support means,

( f) supporting said equipment load beneath said derrick,

(g) connecting lowering means to said equipment load,

(h) lifting said equipment load off said load-support means,

(i) retracting said load-support means from beneath said equipment load,and

(j) lowering said equipment load from the drilling platform into thewater to an underwater wellhead.

2. The method of claim 1 including the step of connecting a pipe stringto the lower end of the equipment load prior to lowering said equipmentload to said wellhead, said pipe string extending through said wellheadinto the well.

a 3. In well drilling, completion and work-over operations carried on atoffshore locations from a drilling platform having a derrick and a hoistsystem therein, a method of handling equipment prior to running saidequipment to an underwater wellhead, said method comprising (a)positioning an equipment load to one side of a derrick on a drillingplatform,

(b) lowering said equipment load by a first hoist means from the levelof the derrick base to a level on said drilling platform entirely belowsaid derrick base and to one side thereof,

(c) positioning said equipment load at said lower level for lateralmovement thereat,

(d) moving said equipment load laterally at said lower level frombeneath said first hoist means to a position underneath second hoistmeans,

(e) transferring said equipment load by said second hoist means fromsaid lead moving position to loadsupport means,

(f) supporting said equipment load beneath said derrick on saidload-support means,

(-g) connecting lowering means to the top of said equipment load andconnecting pipe means to the bottom of said load, said pipe meansextending down through the water into an underwater well,

(h) lifting said equipment load off said load-support means,

(i) retracting said load-support means from beneath said equipment load,and

(j) lower-ing said equipment load from the drilling platform into thewater to an underwater wellhead.

4. A drilling platform for drilling oil and gas wells at offshorelocations, said platform comprising a buoyant hull adapted to float in abody of water,

a main deck fixedly secured to the hull, 1

a derrick including hoist means positioned on said main deck, therebeing an unobstructed vertical opening through said drilling platformbelow said derrick hoist means at least of a size to facilitate passageof well casing therethrough,

an auxiliary deck positioned beneath the main deck and the derrickthereon of a size to support heavy well equipment, said auxiliary deckhaving a vertical opening therethrough forming a portion of the verticalopening of said drilling platform, said main deck having a secondvertical opening therethrough to one side of said derrick,

load-carrying means movably secured to said platform between said maindeck and said auxiliary deck and extending laterally between said secondopening in said main deck and said vertical opening in said platform andmain deck beneath said derrick,

said load-carrying means comprising horizontally-dis posed track meanssecured to said platform between said main deck and said auxiliary deck,and carriage means mounted on said track means for transporting a loadthereon,

prime mover means operatively secured to said carriage means for drivingit along said track means,

said track means comprising a pair of spaced tracks positioned onopposite sides of said second opening in said main deck and secured tothe underside of said main deck and extending laterally to a point onopposite sides of the opening through said drilling platform, andwherein said carriage means comprises at least two separableload-supporting dollies.

5. The apparatus of claim 4 wherein said dollies are provided with slingmeans connectible to the undersides of said dollies for hanging a loadtherefrom, and connector means attachable at opposite ends to saiddollies for connecting said dollies together in fixed relationship.

6. The apparatus of claim 4 wherein said track means are mounted on saidplatform close to the underside of the main deck and wherein saidauxiliary deck is provided with laterally-movable load-supporting meansextending 9 across said vertical Opening thereinfor temporarilysupporting a load below said track means and said derrick.

7. The apparatus of claim 6 wherein said load-supporting means comprisesat least a pair of laterally-retractable beams positioned laterally onopposite sides of the vertical opening through said platform and normalto said track means positioned thereabove, said load-supporting meansbeing supported by said auxiliary deck, and base means secured to saidauxiliary deck for supporting said beams in their retracted position toone side of said vertical opening.

3. The apparatus of claim 4 including a sheave dolly mounted for slidingmovement along said track means, said sheave dolly including a pluralityof vertically-positioned sheaves, at least two guide cables passing overtwo of said sheaves and extending downwardly to an anchored positionbelow the surface of a body of water, means for applying substantiallyconstant tension to the other ends of said guide cables, said sheavedolly being normally positioned on said track means so that the guidecables are positioned substantially vertically in the vertical openingof said drilling platform beneath the hoist means of said derrick, saidsheave dolly and said guide cables being adapted to be moved to one sideof said normal position.

Reterences Cited by the Examiner UNITED STATES PATENTS 1,829,304 10/31Schroeder 175-10 2,756,021 7/56 Townsend l758 2,981,346 4/61 Bauer et a1175-5 3,021,909 2/62 Postlewaite l757 3,043,255 7/62 Bauer et a1 l757CHARLES E. OCONNELL, Primary Examiner.

1. IN WELL DRILLING, COMPLETION AND WORK-OVER OPERATIONS CARRIED ON ATOFFSHORE LOCATION FROM A DRILLING PLATFROM HAVING A DERRICK AND A HOISTSYSTEM THEREIN, A METHOD OF HANDLING EQUIPMENT PRIOR TO RUNNING SAIDEQUIPMENT TO AN UNDERWATER WELLHEAD, SAID METHOD COMPRISING (A)POSITIONING AN EQUIPMENT LOAD TO ONE SIDE OF A DERRICK ON A DRILLINGPLATFORM, (B) LOWERING SAID EQUIPMENT LOAD FROM THE LEVEL OF THE DERRICKBASE TO A LEVEL ON SAID DRILLING PLATFORM ENTIRELY BELOW SAID DERRICKBASE AND TO ONE SIDE THEREOF, (C) POSITIONING SAID EQUIPMENT LOAD ATSAID LOWER LEVEL FOR LATERAL MOVEMENT THEREAT, (D) MOVING SAID EQUIPMENTLOAD LATERALLY AT SAID LOWER LEVEL TO A POSITION UNDERNEATH THE HOISTSYSTEM OF SAID DERRICK, (E) TRANSFERRING SAID EQUIPMENT LOAD FROM SAIDLOAD MOVING POSITION TO LOAD-SUPPORT MEANS, (F) SUPPORTING SAIDEQUIPMENT LOAD BENEATH SAID DERRICK, (G) CONNECTING LOWERING MEANS TOSAID EQUIPMENT LOAD, (H) LIFTING SAID EQUIPMENT LOAD OFF SAIDLOAD-SUPPORT MEANS, (I) RETRACTING SAID LOAD-SUPPORT MEANS FROM BENEATHSAID EQUIPMENT LOAD, AND (J) LOWERING SAID EQUIPMENT LOAD FROM THEDRILLING PLATFORM INTO THE WATER TO AN UNDERWATER WELLHEAD.